I went to IR's website and this Reference design is not yet being sold. But the other ones all cost about $300 each. Here is the link to thier ref design page.
Well sinsinsin49 is right. The IR Class-D Audio Amp exists for quite some time but I never got a response from IR regarding a suitable SMPS. I was working on a DJ surface controller two years back and we intended to include an AMP right into the unit so that a portable party machine could be realized. But dropped it due to the SMPS issues. Also DC protection is important. Who wants $$$$ speakers to be fried !!!
These IR Class-D modulators are closed loop, and as such can run quite happily on a basic (and cheap) unregulated power supply. The PSRR of this design is roughly comparable to other closed loop A and AB designs.
Power supply pumping is definitely a very real issue, and many half-bridge stereo amplifiers run the two channels out of phase and reverse the speaker output terminals on one channel to preserve absolute phase on both channels. Since power supply pumping tends to be a low-frequency, high amplitude issue, and low-frequency content in most program material is pretty "mono", this approach effectively eliminates any danger from power supply pumping.
btw, Radio and other kinds of tubes known as Audion, valve, Triode, etc. are patented by some and developed by others. Tesla deserves a mention in this circle and, in general, naming a device is sufficient as there is much uncertainty about the personalities behind 'ownership' of any technology.
Curious article, I see more work in Class D amps which seem to have never been mentioned in Audiophile circles(at least I only hear it in derision and casual glances)...My take on it is that the 'D' System will ultimately be less reliable than a comparable Class A system. You will need digital filtering and expensive power supply components, quite a bit more complex designs and similar high-priced devices...I am surprised the Japanese authors seem to be unaware of their forefathers' interest in Hi-Fi, as they made some really high quality gear in the 70's and 80's! The first statement gets me too...as cost was seldom an issue in the pursuit of premium sound in those days; 'trade-off' seldom entered the conversation! If I ever run across a 'stereo system' touting Class D innards, I'll be sure to have a careful listen.
"Class D topology is perfect in theory. It is free from non-linearity, meaning there is zero distortion"
Boy, these guys have got a big disappointment coming! The best switching amplifiers can perform well and sound great, but let's take it easy with the hyperbole.
So when is the author going to release it in kit form or fully assembled?
Also what is the max current for the +/- 50Vdc power supply and how much noise is allowed on these lines (ie: can a switchmode power supply be used?)
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